Disconnect hinge apparatus



Oct. 31, 1961 A. J. DUBAN DISCONNECT HINGE APPARATUS Filed Aug. 4, 1959 INVENTOR.

ANTHONY J. DUBAN ATTORNEY ilnired States 3,@05,0Z Patented Oct. 31, 1961 ice 3,0-06,tl25 DISCONNECT IHNGE APPARATUS Anthony J. Duhan, Fort Worth, Tex., assignor to General Dynamics Corporation, San Diego, Calif., a corporation of Delaware Filed Aug. 4, 1959, Ser. No. 831,645 Claims. (Q1. 16-176) The present invention relates generally to disconnect hinge apparatus, and more particularly relates to hinges which can be rapidly and easily disconnected and re-co-unected at their axis or hinge pivot line.

There are numerous situations in which hinges are used where it is desirable and often necessary to be able to disconnect, and then re-engage, the hinges. Common examples of such situations are those in which hinged aircraft access doors, panels, leading edges and the like must be fully removed from the aircraft to permit maintenance and service of the 'aircrart. At other times it may be desirable to disengage a hinge merely to increase exterior access room or to replace a worn hinge pin.

Prior to development of the present invention this hinge disconnection operation was generally accomplished by pulling the hinge pin from the hinge, allowing the two plates of the hinge to be separated. This approach, however, suffers serious disadvantages during the re-engargement operation when a long and relatively thin hinge pin, such as that utilized in piano type hinges, must be forcibly pushed back through a plurality of hinge nodes. In such a re-engagement operation the hing pin frequently buckles, bends, jams, or otherwise becomes useless. Past experience has shown that many re-engagement or reconnection attempts and many hinge pins are often used to reassemble one hinge. Such operations prove costly through waste in man hours and material. Perhaps even more important though, is the effect of such operations on the available flight time of an aircraft.

The present invention however, is specifically designed to overcome these disadvantages. Accordingly, an object of the present invention is to provide a disconnect hinge apparatus that can be easily and rapidly disconnected and re-cormected.

Another object is to provide a disconnect hinge apparatus that will reduce material waste and man hour expenditure.

Another object is to provide a disconnect hinge apparatus for use with aircraft doors, panels and the like.

And still other objects and features of the present invention will be readily apparent to those skilled in the art from the following specification and appended drawing wherein is illustrated a preferred form of the invention, and in which:

FIGURE 1 is a perspective view of the disconnect hinge apparatus in its fully disconnected state, with a central portion of the apparatus broken out to compress the length of the illustration;

FIGURE 2 is a perspective showing of a portion of the disconnect hinge apparatus wherein one hinge plate is engaged with the hinge pins;

FIGURE 3 is a perspective view of a fully assembled disconnect hinge apparatus; and

FIGURE 4 is a cross-sectional view taken along line lVlV of FIGURE 3, showing the present invention as it may be used on an aircraft.

Referring now to the drawing, the present invention is shown therein as generally comprised of two hinge plates 10, 11 and a strap member 12 Hinge plates 10 and 11 are relatively flat plate members formed in substantially longitudinal rectangular shapes. Hinge plate 10 has longitudinal edges 13, 14, while hinge plate 11 has longitudinal edges 15, 16. A plurality of substantially cylindrical hinge nodes 17 protrude lateraly from edge 14 of hinge plate 10 and are evenly spaced 'along the edge thereof with cylindrical axes parallel thereto. Each node 17 has a cylindrical hole 18 disposed axially therethrough parallel to the longitudinal edge 14, which holes are adapted to receive hinge pins. It is noted that each node 17 is offset somewhat in a direction normal to the flat portion of hinge plate 10 so that the lower surface 19 of hinge plate 10 extends to and meets each node tangentially.

Similarly, hinge plate 11 includes a plurality of substantially cylindrical nodes 21 which protrude laterally from longitudinal edge 16. Nodes 21 are positioned with their cylindrical axes parallel to edge 16 and each contains a hole 22 disposed axially therethrough to receive a hinge pin. The nodes 21 are offset in a direction normal to the flat portion of hinge plate 11 so that lower surface 25 of hinge plate 11 extends to and meets each node tangentially. The nodes 21, just as nodes 17, are evenly spaced apart save for an end node or stop 26, which does not serve the same function as nodes 21. Hinge plate 11 includes another end node or stop 27 at its other end which also serves a function different from that of nodes 21, as will be seen later from a description of the use and operation of the disconnect hinge apparatus. The nodes 21 of hinge plate 11 are spaced apart the same distance as the nodes 17 of hinge plate 10', and both hinge plates have a plurality of rivet holes, designated by the numerals 23 and 24, located along their length to facilitate attachment of the hinge plates to other structure. Naturally though, it is understood that other means of attachment can be used if desired.

The strap member 12 is somewhat similar in shape to the hinge plates in that it too has a substantially longitudinal rectangular shape. Strap member 12 is also relatively flat, having a flat upper surface 30 and a flat lower surface 31. A plurality of right angle studs 32 are secured to the fiat upper surface 30. The studs are substantially evenly spaced along the length of the upper surface in a straight line. Each stud has one flat rectangular leg 33 secured to the upper surface 30 and a second flat rectangular leg 34 protruding normally from the upper surface 30. Each leg 33 of the studs is spot welded to the flat portion. of strap member 12, with the legs 33 all pointing toward end 35 of the strap member and legs 34 forming planes normal to the longitudinal axis of the strap member. It is understood though, thatother means could be used to make the studs an integral part of the strap member.

A plurality of hinge pins 36 are fixed to legs 34 of the studs in such a manner that all point toward end 37 of strap member 12;. The hinge pins are all aligned with one another to form a relatively straight line. Each hinge pin protrudes normally from a stud leg 34 and lies parallel to flat surface 30 of the strap member. The distance be tween each hinge pin and flat surface 30 is essentially equal to the distance between the holes in each hinge node and the lower surface of their respective hinge plates. Each hinge pin is of such a length as to fully protrude through two hin e nodes placed side by side thereon. The ends 38 of the hinge pins are pointed, beveled, or chamfered so that precise alignment with the holes in the hinge nodes is not a prerequisite for insertion of the hinge pins into such holes.

Attention is directed to the spacing of the studs32 on strap member 12. It is noted that the distance between the end of each hinge pin and the next, or adjacent, stud leg 34 is such that only one hinge node at a time can be positioned therebetween in preparation for engagement on the hinge pins. It will be seen that this particular spacing arrangement produces the highest linear density of nodes possible in the present invention, thereby effecting the most structurally reliable hinge.

In addition to the studs and hinge pins described, the strap member 12 also includes a nut flange 41 securely attached to end 35 thereof. Nut flange 41 has a threaded hole positioned the-rethrough in alignment with hinge pins 36. A screw 42 is disposed through the hole and threadedly engaged therewith. Screw 42 is aligned with hinge pins 36 and is axially adjustable to move toward and away from the hinge pins. The end 43 of screw 42 is ground off into a square shape to facilitate axial adjustment of the screw. The opposite end 44 of the screw is pointed, with the point directly in line with, and pointing in the same direction as, hinge pins 36.

Similarly, a nut flange 45 is fixed to the opposite end 37 of the strap member. Nut flange 45 also has a threaded hole positioned therethrough in alignment with the hinge pins. A screw 46 is threadedly engaged in the hole and is axially adjustable therein in alignment with the hinge pins. The end 47 of the screw is squared off, and the end 48 of the screw is pointed, just as with screw 42. It is noted however, that the pointed end 48 of screw 46 points in a direction opposite to the pointing direction of the hinge pins. These axially adjustable screws 42 and 46 are utilized in the disconnect and reengage operations of the present invention.

As previously mentioned, the disconnect hinge apparatus can be used in many situations where it is desired to be able to rapidly and easily hingedly lock two structural members together and subsequently separate them. In this regard, FIGURE 4 shows the invention in its completely assembled state, with hinge plate 11 secured to an aircraft skin portion 51 by rivets 52, and hinge plate secured to an aircraft panel portion 53 by rivets 54.

In order to arrive at this completely assembled state however, certain operational steps are required. To explain these steps clearly, reference is first made to FIG- URE 1 which shows the apparatus completely disassembled. It should be assumed that hinge plate 10 is already riveted to aircraft panel portion 53, and that hinge plate 11 is already riveted to aircraft skin portion 51. With hinge plate 11 fixed in place and unable to move, strap member 12 is held adjacent thereto in such manner that the nodes 21 of the hinge plate are positioned adjacent the ends of hinge pins 36 of the strap member. Subsequently, movement of the strap member in the pointing direction of the hinge pins causes the hinge pins to enter the holes 22 of nodes 21. The pointed or beveled ends of the hinge pins facilitate the entry of those hinge pins which may not be exactly in line with their respective node holes.

The initial movement of the strap member to insert the hinge pins can generally be done by hand. Once the pins have engaged the nodes however, further insertion may prove diflicult. If this proves to be the case then screw 46 can be brought to bear on end node or stop 26 of hinge plate 11. As screw 46 is thereafter advanced through nut flange 45, toward hinge pins 36, the strap member is advanced in the pointing direction of the hinge pins and the hinge pins are forcibly inserted further into the nodes of binge plate 11. This axial screw adjustment and attendant hinge pin insertion is continued until the hinge pins are substantially fully engaged with nodes 22, as shown in FIGURE 2.

Now the aircraft panel 53 can be placed in its proper location with the hinge plate 10 secured thereto being positioned so that its hinge nodes 17 lie adjacent ends of nodes 21 of hinge plate 11. With nodes 17 in this po sition, the hinge pins can be moved further through nodes 21 to engage nodes 17. As can be seen from FIGURES 1 and 3, one node 17 of hinge plate 10 fits between a node 21 and end node or stop 26 of hinge plate 11. As a result, further advancement of screw 45 will move the strap member in relation to both hinge plates. This further screw advancement will force the: hinge pins completely through nodes 21 and 17 so that they protrude slightly from nodes 17, as illustrated in FIGURE 3. The apparatus has thus been fully engaged to form a hinge, and without the usual hinge pin bending, delays, waste and expense attendant with ordinary hinge mechanisms. Further, the hinge pins are locked in place in the hinge plates by screw 46 abutting the hinge nodes against studs 32 of the strap member. It should also be noted that in this locked position, the end node or stop 27 of hinge plate 11 butts against nut flange 41 at the other end of the strap member. This naturally requires that screw 42 be axially adjusted so that it does not protrude through nut flange 41. If desired however, the locking of the apparatus can be achieved by screw 46 butting against end node or stop 26 and screw 42 butting against end node or stop 27. If this method is used then studs 32 are not subjected to those forces directed along the hinge axis line which are caused by the locking operation.

Of course, another alternative would be to have the distance between end stops 26 and 27 shortened so that locking forces could not possibly be imposed on studs 32, but would always have to be borne by the end stops. Regardless of exactly how the locking is achieved however, it can be seen that a rapid and easy hinge engagement can be achieved with the present invention.

In addition, the disconnection or disengagement of the hinge is every bit as simple and rapid as the engagement operation just described. In order to disconnect the hinge, screw 46 is backed off from end stop 26 and screw 42 is brought to bear on end stop 27. Further advancement of screw 42 through nut flange 41 will cause stnapmember 12 to move in a direction opposite to that of the advancing screw. This motion will be relative to both hinge plates since screw 42 bears on stop 27 of binge plate 11, and nodes 21 of hinge plate 11 bear on nodes 17 of hinge plate 10. Consequently, advancement of screw 42 will cause the hinge pins to be withdrawn from from the hinge nodes. This screw advancement is continued until the hinge pins are fully withdrawn from nodes 17, at which time the hinge plate 14) and aircraft panel 53 secured thereto can be separated from hinge plate 11 and aircraft skin 51. The strap member 12 can then be left in position in hinge plate 11 or withdrawn completely therefrom by further advancement of screw 42 if desired. If the hinge pins are not withdrawn rom the nodes of binge plate 11 then the reconnection of the hinge will be even more simple and rapid than previouslydescribed.

There has thus been described a disconnect hinge apparatus particularly adapted for use in situations where it is desirable to be able to disconnect, and then re-engage,

the hinge apparatus. The description has, for the sake of clarity, been based on a preferred embodiment, but it is understood that alternatives or equivalents may be used that do not vitiate the invention. One area that readily lends itself to alternate structure is the locking and unlocking mechanism used on the strap member. One approach to the problem would be the use of linkage lever arms similar to those used on suitcases. Then too, the ability of the apparatus to be locked in place does not require that both end stops (or nodes) be on the same hinge plate. In view of these structural alternatives, and others that will be readily apparent to those skilled in the art, the invention is to be given its broadest possible interpretation within the terms of the following claims.

What I claim is:

1. Disconnect hinge apparatus comprising first and second hinge plates and a strap member, said strap member having a plurality of hinge pins spaced apart from each other and each being aligned and pointed in substantially the same direction as adjacent hinge pins, said hinge pins being positioned between the lateral edges of said strap member, each said hinge plate having a plurality of hinge nodes adapted to fit on said plurality of hinge pins, each of said hinge pins accommodating a first plate hinge node and a second plate hinge node, and said hinge pins being of a length to completely project through said hinge nodes of said first and second hinge plates.

2. Disconnect hinge apparatus comprising first and second hinge plates and a strap member, said strap member having a plurality of hinge pins fixed thereto, said hinge pins being positioned intermediate the lateral edges of said strap member, said hinge pins spaced apart from each other with each hinge pin aligned and pointed in substantially the same direction as adjacent hinge pins to provide a hinge axis, each said hinge plate having a plurality of hinge nodes adapted to fit on said plurality of hinge pins, each of said hinge pins completely projecting through at least one of said hinge nodes of said first and second hinge plates and movement of said strap member relative to said hinge plates along said hinge axis causing said hinge pins to hingedly secure said hinge plates together and disengage said hinge plates as prescribed by the direction of said movement.

3. Disconnect hinge apparatus comprising first and second hinge plates and a strap member, said strap member having a plurality of hinge pins fixed thereto, said hinge pins being positioned intermediate the lateral edges of said strap member, said hinge pins spaced apart from each other with each hinge pin aligned and pointed in substantially the same direction as adjacent hinge pins to provide a hinge axis, each said hinge plate having a plurality of hinge nodes adapted to fit on said plurality of hinge pins, said spacing between said hinge pins being sufficient to permit insertion of at least one node between each pair of adjacent hinge pins in position for engagement with one of said hinge pins, each of said hinge pins being of sufiicient length to project completely through at least one of said hinge nodes of said first and second hinge plates, movement of said strap member relative to said hinge plates in the direction of said hinge pins securing said hinge plates together in a hinge arrangement when said nodes are positioned between said hinge pins, and subsequent movement of said strap member relative to said hinge plates in the opposite direction disengaging said hinge plates from said hinge arrangement.

4. Disconnect hinge apparatus comprising first and second hinge plates and a strap member, said strap member being substantially elongated in shape and having a plurality of stud members fixed thereto, said stud members spaced apart from each other and disposed in a substantially straight line, each said stud member having a hinge pin fixed thereto, said hinge pins being aligned and pointed in substantially the same direction, said hinge pins being positioned intermediate to the lateral edges of said strap member, each hinge pin pointing toward a stud member adjacent the stud member to which said hinge pin is secured, each said hinge plate having a plurality of hinge nodes adapted to fit on said plurality of hinge pins, and each of said hinge pins completely projecting through at least one of said hinge nodes of said first and second hinge plates.

5. Disconnect hinge apparatus comprising first and second hinge plates and a strap member, said strap member being substantially elongated in shape and having a plurality of stud members fixed thereto, said stud members being evenly spaced apart in a substantially straight line, each said stud member having a hinge pin fixed thereto, said hinge pins being aligned and pointed in substantially the same direction with each pin pointing toward a stud member adjacent the stud member to which said pin is secured, said hinge pins being positioned intermediate the lateral edges of said strap member, each said hinge plate having a plurality of hinge nodes adapted to fit on said plurality of hinge pins, said studs being spaced apart a distance which permits insertion of at least one of said nodes between each stud and the hinge pin of an adjacent stud in position for engagement with said hinge pin of said adjacent stud, and each of said hinge pins projecting completely through a first plate hinge node and a second plate hinge node to hingedly secure said hinge plates together.

6. Disconnect hinge apparatus comprising first and second hinge plates and a strap member, said strap member being substantially elongated in shape and having a plurality of stud members fixed thereto, said stud members being evenly spaced apart in a substantially straight line, each said stud member having a hinge pin fixed thereto, said hinge pins being aligned and pointed in substantially the same direction with each pin pointing towards a stud member adjacent the stud member to which said pin is secured, said hinge pins being positioned intermediate the lateral edges of said strap member, each said hinge plate having a plurality of hinge nodes adapted to fit on said plurality of hinge pins, said studs being spaced apart a distance which permits insertion of at least one of said nodes between each stud and the hinge pin of an adjacent stud in position for engagement with said hinge pin of said adjacent stud, and each of said hinge pins completely projecting through at least one of said hinge nodes of said first and second hinge plates.

7. Disconnect hinge apparatus comprising first and second hinge plates and a strap member, said strap member including a plurality of hinge pins, said hingepins spaced apart from each other and aligned and pointed in substantially the same direction to provide a hinge axis, said hinge pins being positioned intermediate the lateral edges of said strap member, said hinge plates each being a substantially fiat and longitudinal plate having at least one relatively straight longitudinal edge, each said hinge plate having a plurality of hinge nodes disposed adjacent said relatively straight longitudinal edge, said nodes spaced apart in such a manner as to permit their engagement with said strap member hinge pins when positioned therebetween, each said hinge pin completely projecting through at least one of said hinge nodes of said first and second hinge plates, movement of said strap member relative to said hinge plates in the direction of said hinge pins securing said hinge plates together in a hinge arrangement when said nodes are positioned between said hinge pins, and subsequent movement of said strap member relative to said hinge plates in the opposite direction disengaging said hinge plates from said hinge arrangement.

8. Disconnect hinge apparatus comprising first and second hinge plates and a strap member, said strap member including a plurality of hinge pins, said hinge pins spaced apart from each other and aligned to form a substantially straight line With said hinge pins all pointing in the same direction along said line, each said hinge plate including a plurality of hinge nodes spaced apart in such a manner as to permit their engagement with said hinge pins when positioned between said hinge pins, movement of said strap member relative to said hinge plates in the direction of said hinge pins securing said hinge plates together in a hinge arrangement when said nodes are positioned between said hinge pins, said hinge pins being of a length to completely project through said hinge nodes of said first and second hinge plates, subsequent movement of said strap member relative to said hinge plates in the opposite direction disengaging said hinge plates from said hinge arrangement, and means carried on said strap member and engaging said hinge plates along the axis of said hinge pins to effect the locking and unlocking of said hinge pins from within said hinge nodes.

9. Disconnect hinge apparatus comprising first and second hinge plates and a strap member, said strap member including a plurality of hinge pins, said hinge pins spaced apart from each other and aligned to form a substantially straight line with said hinge pins all pointing in the same direction along said line, each said hinge plate including a plurality of hinge nodes spaced apart in such a manner as to permit their engagement with said hinge pins when positioned between said hinge pins, movement of said strap member relative to said hinge plates in the direction of said hinge pins securing said hinge plates together in a hinge arrangement When said nodes are positioned between said hinge pins, said hinge pins being of a length to completely project through said hinge nodes of said first and second hinge plates, subsequent movement of said strap member relative to said hinge plates in the opposite direction disengaging said hinge plates from said hinge arrangement, and rotatable means in said strap member contacting said hinge plates along the axis of the hinge pins for efiecting longitudinal movement of said strap member with respect to said hinge plates.

10. Disconnect hinge apparatus comprising first and second hinge plates and a strap member, said strap member being substantially longitudinal and having first and second ends, said strap member having a plurality of hinge pins disposed along its length, said hinge pins spaced apart and arranged in a substantially straight line to effect a hinge axis withall said hinge pins pointing toward said first end of said strap member along said axis, a nut flange disposed at said first end of said strap member, an axially adjustable screw positioned through said nut flange in line with said hinge axis, each said hinge plate including a plurality of hinge nodes spaced apart in such a manner as to permit their engagement with said hinge pins when positioned endwise adjacent thereto, said nodes of said second hinge plate engaged with said hinge pins and said hinge pins protruding from said nodes to accommodate said nodes of said first hinge plate, said first hinge plate nodes positioned endwise adjacent said hinge pins with one of said nodes being an end node substantially adjacent said axially adjustable screw, said screw adjustable to bear on said node, and axial movement of said screw toward said hinge pins forcibly coercing said hinge pins into said nodes of said first hinge plate to effect a hinge arrangement between said first and second hinge plates.

11. Disconnect hinge apparatus comprising first and second hinge plates and a strap member, said strap member being substantially longitudinal and having first and second ends, said strap member having a plurality of hinge pins disposed along its length, said hinge pins spaced apart and arranged in a substantially straight line to effect a hinge axis with all said hinge pins pointing toward said first end of said strap member along said axis, a nut flange disposed adjacent said second end of said strap member, and axially adjustable screw positioned through said nut flange in line with said hinge axis, each said hinge plate including a plurality of hinge nodes spaced apart in such a manner as to permit their engagement with said hinge pins, said nodes of said hinge plates positioned on said hinge pins, one of said hinge plates having a stop positioned between said axially adjustable screw and said hinge pins, said screw adjustable to bear on said stop, and axial movement of said screw towards said hinge pins forcing the nodes of at least one hinge plate of]? said hinge pins.

12. Disconnect hinge apparatus comprising first and second hinge plates and a strap member, said strap member being substantially elongated in shape and having a plurality of right angle studs fixed thereto, one leg of each right angle stud being secured to said strap member and the other leg protruding normally therefrom, said normally protruding legs spaced apart and arranged in a substantially straight line, one hinge pin fixed to each normally protruding stud leg, said hinge pins all arranged to point in the same direction and line along one line to effect a hinge axis, said hinge pins being positioned intermediate the lateral edges of said strap member, each said hinge plate having a plurality of hinge nodes adapted to fit on selected hinge pins, and each of said hinge pins completely projecting through at least one of said hinge nodes of said first and second hinge plates whereby a hinge arrangement is produced.

13. Disconnect hinge apparatus comprising first and second hinge plates and a strap member, said strap member including a plurality of hinge pins, said hinge pins spaced apart from each other and aligned and pointed in substantially the same direction to provide a hinge axis, said hinge pins being positioned intermediate the lateral edges of said strap member, said hinge plates each being a substantially flat and longitudinal plate having at least one relatively straight longitudinal edge, each hinge plate having a substantially flat lower surface, each said hinge plate having a plurality of hinge nodes protruding laterally from said relatively straight longitudinal edge, each said node having a substantially cylindrical shape, said lower surface of each hinge plate extending to and meeting each node tangentially, said nodes spaced apart in such a manner as to permit their engagement with said strap member hinge pins when positioned therebetween, each said hinge pin completely projecting through at least one of said hinge nodes of said first and second hinge plates, movement of said strap member relative to said hinge plates in the direction of said hinge pins securing said hinge plates together in a hinge arrangement when said nodes are positioned between said hinge pins, and subsequent movement of said strap member relative to said hinge plates in the opposite direction disconnecting said hinge plates from said hinge arrangement.

14. Disconnect hinge apparatus comprising a first hinge plate, a second hinge plate, a plurality of hinge pins spaced apart and aligned in a substantially straight line, said hinge pins all pointing in the same direction, holding means fixed to said hinge pins for securely holding each hinge pin in its position relative to the other hinge pins, said hinge pins being positioned intermediate the lateral edges of said holding means, each said hinge I plate having a plurality of hinge nodes adapted to fit on a plurality of said hinge pins, said hinge pins being of a length to completely project through said hinge nodes of said first and second hinge plates, movement of said holding means relative to said hinge plates in the direction of said hinge pins securing s id hinge plates together in a hinge arrangement when said nodes of said hinge plates are positioned for engagement with said hinge pins, and subsequent movement of said holding means relative to said hinge plates in the opposite direction disconnecting said hinge plates from said hinge arrangement.

15. Disconnect hinge apparatus comprising first and second hinge plates and a strap member, said strap member being substantially longitudinal and having first and second ends, said strap member having a plurality of hinge pins disposed along its length, said hinge pins spaced apart and arranged in a substantially straight line to efiect a hinge axis, a nut flange disposed at said first end of said strap member, an axially adjustable screw engageable with said nut flange in line with said hinge axis, each said hinge plate including a plurality of hinge nodes spaced apart in such a manner as to permit their engagement with said hinge pins when positioned endwise adjacent thereto, said hinge pins being adapted to project completely through said nodes of said first and second hinge plates, said first hinge plate nodes positioned endwise adjacent said hinge pins with one of said nodes being an end node substantially adjacent said axially adjustable screw, said screw being adjustable to bear on said node, and axial movement of said screw toward said hinge pins forcibly moving said hinge pins into said nodes of said first hinge plate to eflect a hinge arrangement between said first and second hinge plates.

References Cited in the file of this patent UNITED STATES PATENTS 863,128 Aebi Aug. 13, 1907 1,030,801 Berault June 25, 1912 1,141,828 Rhody June 1, 1915 1,320,143 Hartman Oct. 28, 1919 2,273,455 Whitman et al Feb. 17, 1942 2,444,114 Pevney June 29, 1948 

